The Research and Design of Electronic Current Transformer Based on PCB Planar-Type of Air Core Coil

A new current transformer based on planar air core coil was presented in this article. The secondary coil of sensor was implemented on printed circuit boards and each PCB contains two coils in opposite directions to eliminate the impacts of outside magnetic field by the greatest degree. Moreover, multilayer boards were connected to improve mutual inductance. The PCBs were embedded in the primary coil which was designed into special shape. The coil´s coefficient of mutual inductance was derived, the influence of external magnetic field was analyzed through ANSYS. The result shows that the special shaped primary coil can produce intensive magnetic field to produce large electrical potential signal and the influence of other two phases can be ignored. Simulation components were influenced easily by temperature, to solve the problem, digital integral was applied in processing circuit .Experimental model was designed, and the linearity and accuracy test results show that the transformer model has high accuracy and strong anti-electromagnetic interference ability.